Multiplex method and system for the transmission of radiant energy



Nov. 16,1926. 1,607,157 J. H. HAMMOND, IR

MULTIPLEX METHOD AND SYSTEM FOR THE TRANSMISSION OF RADIANT ENERGY Original Filed 00% 8, 1917' 2 Sheets-Sheet 1 WITNESS: INVENTOH i 1/"! I I I I Q HIS A TTORNEY Nov. 16 1926. I 1,607,157 J. H. HAMMOND. JR

MULTIPLEX METHOD AND SYSTEM FOR T- ZE TRANSMISSION OF RADIANT ENERGY Original Filed 06"" 1917 2 Sheets-Sheet 2 www My HIS ATTORNEY Patented Nov. 16, 1925;,

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J'OI-IN HAYS HAMMOND, Ja, on enoucnsrnn, MAss cHUsnrTs.

MULTIPLEX METHOD AND srsrnia ron rn'n TRANSMISSION OF RADIANT ENERGY.

Application filed. October 18, 1917, Serial No.197,259. I R'eiiewedluly 24, 1923.

Some of the objects of this invention are to provide an improved multiplex transmission system for radiant energy; to provide an im )roved multi leX receivin s stem for radiant energy; and to provide other improvements as will appear hereinafter;

'In the-accompanying drawings, Fig. 1 is a diagrammatic representation of a transmission system constructed in accordance with this invention; and Fig. 2 is a diagrammatic representation of a multiplex receiving system constructed in accordance with this invention.

The transmission system shown in Fig. 1 comprisesanopen, aerial circuit 10 including an antenna 11 anda coil 12, through which the antennais grounded at 13. The coil.12 forms the secondary of'a step-up transformer 15, which includes a primary coil 16. The coil 16 forms part of a closed, oscillatory circuit 20, which includes a spark gap device 21 and a primary, variable condenser 22. The closed circuit is arranged to beenergized bymeans of a direct current generator 25 or other suitable source of electric current. One pole of the generator 25 is connected by a conductor 26 to one end of a choke coil 27, the other end of which is connected by a conductor 28 to one side of-the variable condenser 22. The other pole of the generator '25 is connected through a variab leresistance 8 0 to one end of a choke coil 31, the other end'of which is connected by a conductor 32- to the other side of the variable condenser 22. The closed circuit 20 is adjusted in such a: manner as to transfer the maximum amount of energy to the open, aerial circuit 10 which may be tuned,

for instance, to 1,000,000 oscillations per.

second. it a I a a I For selectively impressing upon the high frequency oscillations emitted by the open, aerial circuit 10, any one of a plurality of series of periodic amplitude variations having different,- predeterniined frequencies respectively, this nvention provides -a secondary frequency controller '35, which is .con-

1 nected across the, primary, variable condenser 22 and which includes a tone circuit comprising an inductance 36 and a variable,-

secondary condenser 37 in series therewith. This tone circuit 36, 37 may be normally tuned to .anydesired frequency, for instance, to 40,000 oscillations per second and acts to ianpress series of periodic amplitude variations of a corresponding frequency upon the oscillations set up in the closed circuit 20. 1 I v For modifying the periodicity of the tone circuit 36, 37 and consequently the second-- ary frequency of the system, the auxiliary,

variable condensers 40 and 41 are connected across the secondary condenser 3'7and are arranged to be controlled respectively by two keys .42, and 43, which are normally held open by two spiral springs 44 and 45. When either of these keys 42 and 43 is open,

the corresponding auxiliary condenser 40 or 411s rendered inoperative and when either of these keys is closed, thecorresponding condenser 40 M41 is renderedv operative to vary the'periodicity of the tone circuit 36, 37. The auxiliary condensers 40 and 41 may be arranged tomodify the periodicity of the tone circuit '36, '37 in any desired manner. For instance, the arrangement maybe such that, when the key 42 is open and the key 43 is closed, the frequency of the oscillations :in the tone circuit 36, 37, 41 will be 30,000 per second, and when the key 43 is open and the key 42is closed, the frequency of the tone circuit .36, 37, 40' will be 25,000 per second, while when bo'th keys are closed the frequency, of the tone circuit 36, 37, 40, 41 will be 20,000 per second; I It is therefore thought to be evident that this invention provides a transmission or odic amplitude variations may be received u Jonan suitable, rec'eivin s 'StQlTl for in- V b I stance on V the receiving system hereinafter described.

In .Fig. 2 is sh own one form of multi} plex, selective, receiving system constructed in accordance with thisinvention and which maybe used in receiving oscillations from the transmission system shown in Fig. 1.

Il -he improyed .receiying system comprises an open, aerial circuit including'an an-- tenna 101' and an inductance coil 102 ro ehwh'i h the antenna 'is grounded at The open circuit 100. is preferably l tuned to the frequency of the received 'osf glass bulb or container 125, in which is arranged a filament 120, a grid 127, and a terminal 128. The filament 126 is arranged to be heated by a battery 130, acting through a variable resistance or rheostat-181. The detector controls a circuit including a battery 185 and three coils 136, 137 and 138.

Connected across these coils respectively are three, variablecondensers 140, 141 and 142,

which form with the coils three, closed, secondary oscillatory circuits 148, 144 and 14 which are preferably tuned respectively to three different, secondary frequencies, for instance, 80,000 cycles per second, 20,000

cycles per second, and 25,000 cycles per sec- 0nd, to correspond with the tuning mentioned in connection with the description of the transmission system shown in Fig. 1.

The three, closed, secondary, oscillatory circuits 143, 144 and 145 are inductively connected to three, closed, controlled circuits 150,

151 and 152, which include respectively three coils 153, 154 and 155 and three variable condensers 156, 157 and 158. These'three controlled circuits 150, 151 and 152 are tuned respectively to the frequencies o1 the controlling secondary circuits 143, 144 and 145 and are arranged to act through three stoppage condensers 165, 106 and 167 to control three secondary oscillation detectors 170, 171 and 172. These secondary detectors 170, 171 and 172 may be of any suitable construction, for instance, or" thesame construction as the primary detector 120, and are arranged to control respectively three circuits including respectively three batteries 175, 17 6 and 177 and three coils 178, 17 9 and 180. Connected across the three coils 178,

, 179 and 180 are three variable condensers ilii V quency,

185, 186 and 187 which form with the coils three, closed, oscillatory circuits 190, 191 and 192, which are each tuned to a: trefor instance, of 1,000 cycles per second to cause the circuits to oscillate in response to a corresponding beat frequency which is set up as will appear hereinafter 'in the closed circuits 150, 151 and 152, controlling the three vsecondarydetectors 170,

' 171 and 172.

' The two closed circuits 190 and 191 are inductively connected to a common, closed circu 195, which includes a coil an'd a vauable condenser 197 and'is tuned to a trei,eo7,157

quency, for instance, of 1,000 oscillations per second. This latter circuit is arranged to control an oscillation detector 198 constructed iii any well-known or suitable manner or as hereinafter described and arranged to control a circuit containing a battery 199 and a telephone 200 or other receivingin' struinent or device. V

The two circuits 191 and 192 are inductively connected to a common, closed, oscillatory circuit 205, which includes a coil 206 and a variable condenser 207 and is arranged to control an oscillation detector 208, constructed in any Well-known or suitable manner or as hereinafter described and arranged to control a circuit including a battery 209 and atelephone 210 or other receiving in strument or device.

For producing electrical beats having a frequency 01, for instance, 1,000 cycles per second in each of the closed circuits 150, 151 and 152 which control the secondary detectors 170, 171 and 172 any suitable means may be provided for-instance, three local sou cesot oscillations 215, 210 and 217 of well-known construction may be provided for this purpose. These local sources of oscillations coinpriserespectively three oscillatory circuits 218,219 and 220 which are arranged to be controlled respectively by three thermionic valves 221, 222 and 223 acting respectively through three batteries 224, 225 and Each of the three closed circuits 218, 219 and 220 is tuned to oscillate either at a frequency 1,000 oscillations per second above or 1,000 oscillations per second below the frequency of oscillation of the ciiu'irsponding, closed, control circuit 150, 151 or 152. For instance, the closed circuit 218 may be tuned to oscillate either at 29,000 or 31,000 cycles per second, and theclosed circuit 219inay be tuned to oscillate either at 19,000 or 21,000 cycles per second, while the thirdclosed circuit 220 may be tuned to oscillate either at 24,000 01 26,000 cycles per second. These three closed circi'sits 218, 220 are connected respectively .with the corresponding control circuits 150, 151 and 152, through three electrostatic couplings 230, 231 and 282 containing respectively three variable condensers 233,234 and 235. 3

In the operation of the receiving system shown in Fig; 2 with the transmission system shown inFig. 1, when both keys 42 and 43 of the transmission system are open, i

the transmission system will emit a series of oscillations having, tor instance, a frequency of 1,000,000 oscillations per second and having impressed. thereon a secondary frequency or series of periodic amplitude variations of, for instance, 40,000 cycles per second. This series of oscillations will affect the open aerial circuit 100 and the primary detector 120 but will not build up oscillations in any iii-iii ,48 is left open. The transmission system will now emlt oscillations having a high freof the Secondary closed circuits 143, 14,41 and 145, and therefore will not affect any of the secondary detectors 170, 171 and 172 or the telephones 200' and 210. But these oscillations Will serve to. confuse any operator who attempts to listen in upon the. sys tem and will also act to 1ncrease the efii ciency and responsiveness of the transmlssion system.

VVhen'it isdesired to Control the telephone receiver 210 of the receiving system of Fig. 2, the corresponding key 1-2 of the trans mission sy stein is closed and the. otherkey quen'cy of 1,000,000 per second with a secondaryfrequency of 25,000 per second and will act in awvell-known manner to energize the antenna 100 and to set up oscillations having a frequencyof 25,000 per second in the corresponding secondary closed circuit 145 of the receiving. system. These oscillations in the secondary circuit 145 will cause ccrrespondin" oscillations of 25,000'per' second in the closed control circuit1 52 which will be acted upon by the oscillations of either 2% 000 per secondor 26,000 per sec-v ond produced by the corresponding-local source of oscillations 217, thus setting up 1 electrical beats inwthe closed circuit 152',

having a frequency of 1,000per second. The corresponding. secondary detector 172 acts in awell-knownmanner to cause oscillations of afrequency of 1,000 cycles per second' frequency 1,000,000 per second? and asecondary frequency orperiodic amplitude variations of 30,000 per second. This series of oscillations acts through the openjaerial circuit 100,,the primary detector lpthe closed'secondary circuit 143, the controlled secondary circuit 150, and the correspond ing'detectors 170 and 198' toc'ontrol the 'tele phone 200 underthe influence of the electrical'be'ats of 1,000 per secondproduced in the controlled secondary circuit 150 in a-manner similar to lthatfiust describedin connection with the control of theother telephone 210.

' l-Vhen it"is desired to'control both receiving telephones 200 and 210 simultaneously, both keys &"2 and'43'ofthe transmission systein are simultaneously closed, and the. open,

aerial circuit thereby caused toemit high frequency oscillations of 1,000,000 per second having impressed. thereon a second ary frequency or periodic amplitude variations of 20,000 per second. These oscilla tions 'Will act as hereinbefore described through the receiving circuit 100, the primary. detector 120, -the correspondlng secondary closed circuit 144, "the corresponding closed circuit 151', and the corresponding secondary detector 171 to cause-oscillations of l',000'per second to be set up in the correfluence of the beatsof 1,000 per' second ,set' up in the closed secondary circuit 151' by the action: of the correspondinglocal source of oscillations 216. The secondary circuit" 191,

sponding controlled circuit 191 under the'in consequently, simultaneously controls both offthe closed circuit-s 195 and 205 to si1nu1- taneously operate the two telephones 200 and 210 ashereinbefore described.

For the purpose of rendering this system immune" to theeif'ects of disruptive, static discharges or powerful, forced interference to coils'l78 and 179'of the closed circuits-190 and 191 are preferably disposed so that for simultaneous and equal currents in the circuits 190 and 1.91 the'inductive effects on the common circuit 195 shall be equal and op' posite andshall result in no net inducedcur-, rent in theicircuit1195. Likewis 'theeofls 179 and 180* of the. closed circuits 191a'nd 192 are so disposedi that for simultaneous and equal currents in the circuits 1 91 and 192 the inductive effects on the common circuit 205 shalllb'e equal andoppositeand shall result inno net'induced current in the circuit 205:- Thisdisposition of the coils 178, 179 and*180 Will in no" Wise aifect'the regular operation of the system sinceinthe i course of the regular operation only one of 7 these coils is energized ata time. In the case, howeveigfof "disruptive, static dis charges OI PO WGIfUl, forced interference,

sudden andfabrup't current fluctuations in the open aerial circuit will be-caused,

which will in turn operatethrou-g-lrthe closedcircuit 112 and the oscillation detector'caus1ng sin'ularlyabrupt and sudden current fluctuations in the controlledlcin cuit; 135, 136, 137-, 138. Underthe influence.

of these abrupt and sudden current fluctuations,"\vh ch"will beeithe'r periodic or of a frequency far' removed from the natural frequencies of the closed circuits 143'," 144:,

andl45, the closed circuits 143, 1 1 1, and 1 1-5 Will be equally" stimulated, thus equally stintulating the circuits 150, 151, tion detectors 170, 171, 172

152, the oscillaand the controlled circuitsl90', 191, 192 and, through.

the balanced disposition of the; c'oils178, J

179. befor e'mentioned, in no jwise st-imulating thecircufits 195, 205 or the oscillation "detectors 198, 208, or the telephones 200, 210. 1 It' -is thereforeevident that the to a predetermined frequency,

balanced arrangement of the coils178, 17 9, 180 with respect to the circuits 195, 205 just described, will shield the final detectors 198, 208 and, consequently, the telephones 200, 210 from the undesired effects of static discharges or powerful forced interference.

From the foregoing it is thought to be evident that this invention provides a system whereby two operators may transmit slmultaneously and independently any two desired bodied, it is to be understood that the invention is not limited to any specific construction but might be embodied in various systems without departing from the spirit of the invention 'or the scope of the appended claims; Having thus tion, I claim: I

1. A receiving system for electric oscillations, including an element tuned to a predetermined frequency, a plurality of secondary elements controlled by said firstmentioned element and tuned to a plurality of different frequencies respectively, local means for producing in each-of said secondary elements respectively electrical beats havingthe same frequency in each of said elements, and a plurality of separately operative receiving devices arranged to be controlled by said elements respectively, each of said receiving devices being arranged to be controlled as a result of the action of the said beats in the corresponding secondary element. 7 a

2. A receiving system for radiant oscillations, including a primary element responsive to radiant oscillations and tuned a plurality of secondary elements controlled by said primary element and tuned to different frequencies respectively, separate, local means for producing electrical beats in said secondary elements, and a plurality of refully described this invenceiving devices arranged to be selectively controlled as-a result of the action of said beats.

3. A receiving system for radiant energy comprising a primary receiving element responsive to radiant energy, a plurality of secondary elements tuned to different, superaudible frequencies respectively and arranged to be selectively controlled as a result of the action of-said primary element, means for producing electrical beats in said secondary elements between locally-generated' currents and currents of the different,

super-audible frequencies to which the sec ondary elements are tuned and a plurality of receiving devices arranged to be selec-.

tively controlled as a result of the action of said secondary elements.

a. A receiving system for radiant energy comprising an open, aerial circuit responsive to radiant energy and tuned to a predetermined frequency, three, secondary, closed, oscillatory circuits tuned to three, different, secondary frequencies respectively and arranged to be controlled as a result of the action of said open aerial circuit, three, closed, oscillatory circuits controlled by said secondary circuits respectively, local means for impressing oscillations on said controlled circuits respectively to produce electrical beats therein, and two, separatelyoperative receiving devices arranged to be selectively controlled as a result of the action of said beats in two of said controlled circuits respectively, and to be simultaneously controlled as a result of the action of said beats in the third one of said controlled circuits.

5. The method of transmitting energy which consists in producing a series of electrical oscillations, modifying said oscillations by selectively impressing thereon any one of three series of periodic variations having different frequencies respectively, selectively causing the operation of any one of three suitably tuned receiving elements as a result of said periodic variations respectively and causing the operation of two receiving devices either selectively as a result of the operation of two of the receiving elements or simultaneously as a result of the action of the third receiving element.

6. A receiving system for radiant oscillations, including a primary element responsive to radiant oscillations and tuned to a predetermined frequency, a plurality of secondary elements controlled by said primary element and tuned to different frequencies respectively, local means for producing electrical beats insaid secondary elements, and a. plurality of receiving devices arranged to be selectively controlled as a result of the action of said beats in certain of said controlled elements and to be simultaneously controlled asa result of the action of said beats in another of said controlled elements.

7. A receivingsystem for'radiant oscillations, including a primary element responsive to radiant oscillations and tuned to a predetermined frequency, a secondary element controlled by said primary element, means for producing a single series of electrical beats in said secondary element, and a plurality of'independent circuits adapted to control a plurality of receiving devices, said circuits being arranged to be simultaneously controlled .as a result of the action of said single series of beats, a

8. A receiving system for radiant oscillations, includingmeans for receiving a pluill) plurality; of receiv-in periodic radiant impulses different frequencies respectively, a

g" devices, and means r ality of. series of. h in for actuating said devices either selectively taneously in response in accordance with a. plurality ofsaid series of impulses or simultaneously in response to a single one of said series of impulses.

. 9, A receiving system for'radiant oscillations, including circuits tuned to a plurality of-series of periodic, super-audible impulses having different frequencies respectively, a, plurality of receiving devices and means interposed between said circuits and said receiving devices for 'operating said devices either selectively in accordance with a plurality of said series of. impulses or simulto a single one of said seriesof impulses. 1

10. A receiving system for radiant oscillations, including a circuit tuned to the frequency of a series of periodic superaudibleimpulses, a plurality of receiving circuits, a thermionic valve for, separately controlling each of 'the receiving circuits and beat producing means interposedbetween said circuit and said thermionic valves adapted to produce a single series of beats, for operating said receiving devices in response to said series of beats.

11. In a system of telegraphy, a transmitting system comprising two telegraph keys and means selectively controlled thereby for generating electrical impulses of either of two different frequencies, said means being arranged to generate electrical impulses of a third frequency upon simultaneous operation of said keys, in combination with a receiving system including two receiving devices, means for separately controlling said receiving devices respectively in response to impulses of said two firstmentioned frequencies, and means for controlling said receiving devices simultaneously in response to impulses of said third frequency.

12. A transmitting system comprising a number of separately-operative, controlling elements, and means controlled thereby for selectively generating a larger number of series of impulses having difierent frequencies respectively, in combination with a receiving system having receiving devices equal in number to said controlling elements, means for separately controlling said receiving devices respectively in accordance with a plurality of said series of impulses, and means for operating a plurality of said receiving devices in accord- 'ance with a single series of said impulses.

13. A receiving system including two revalve controlled eleon a plurality of ceiving devices, to twodili'erent frequencies respectively and arranged tocontrol said devicesrespectively and a third circuit tuned to a third frequency and arranged to control both of saiddevices simultaneously.

.14. A. system for receiving high frequency oscillations having impressed there, ona plurality of series "of periodic am plitude variations of different, super-audible, frequencies, comprising a receiving circuit tuned to the frequency of said oscil-- lations, secondary circuits controlled by the first-mentioned circuit and tuned respec} tively to the frequenciesof said series of variations, a receiving device, a closed, oscillatory circuit controlling said device, and two circuits controlled respectively'by said secondary circuits, each. of said two circuits being arranged to control said closed, oscillatory circuit independently of the other and to oppose the other and substantially to counter-balance its effect on said closed, oscillatory circuit when both of said two circuits act simultaneously upon the closed, oscillatory circuit. i I

15. A receiving-e systemincluding two re ceiving devices, two receiving circuitstuned to two different frequencies respectively and arranged to control said devices respectively and a third circuit tuned .to a third frequency and, arranged to control both of said devices simultaneously, the construction-and arrangement being such that when all of said threecircuits are energized substantially equally the eflect of said third circuit upon each of said two devices will be opposed and substantially balanced by the effect of the corresponding one of said first mentioned two circuits. I

16. A system for receiving high frequency oscillations, having impressed thereon a plurality of series of periodic, amplitude variations of different frequencies, comprising a receiving circuit tuned to the frequency of said oscillations, secondary circuits controlled by the first-mentioned circuit and tuned respectively to the frequencies of said series of variations, a receiving device, a control circuit therefor, two circuits separately controlled by said secondary circuits respectively and connected to the circuit of the receiving device to enable the circuit to be separately controlled by either of said two circuits, said two circuits being connected to the circuit of the receiving device in opposition to each other to neutralize their efiect on the lastmentioned circuit when the two circuits act thereon simultaneously with equal effects.

17. A system for receiving high frequency oscillations having impressed thereseries of periodic, V amplitude variations of different, super-audible frequencies, comprising a receiving circuit two receiving circuits tuned;

ing device, a circuit for controlling the receiving device and two circuits tuned to the frequency of said beats and separately controlled by said secondary circuits respectively, said two circuits being connected to the circuit of the the last-mentioned circuit to be separately receiving device to enable controlled by either of said two circuits and said connections being oppositely arranged to neutralize the effect of the tWo circuits on the circuit of'the receiving device When the two circuits act thereon simultaneously with equal efiects.

"18. -A system for electrical communication comprising a transmitter having a plurality of message controlling devices, a receiver comprising a pluralityof receiving circuits and means at the transmitter and receiver for causing one or a plurality of receiving circuits-to be operated in response to a single message depending upon the selectlon and the manner in whicha single controlling device is operated in sending a message.

19. A system for receiving comprising a plurality of circuits tune re spectively to a plurality of series of superaudible impulses, two receiving devices, means controlled by one of said circuits for operating one of said receiving devices independently ofthe trolled by another of said circuits for operating both of said receivingdevices.

20. A system for electrical communications comprising a receiver including a plurality of receiving circuits, a transmitter,

the transmitter and receiver plurality of the reand means at for causing one or a ceiving devices to be operated in responseto a'single message at the will ofthe operator of the transmitter, in response to the selection and operation of a single modulating means. I

This specification signed this 9th day of October, A. D. 1917. 1

JOHN HAYs- HAMMOND, JR.

radiant energy other, and means con- 

